One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,14)(12,16)(13,17)(15,19)(18,23)(20,22)(21,24)(25,26,31,34)(27,35,37,30)(28,38,40,32)(29,39,36,33)(1,2)(3,6)(4,7)(5,8)(9,11)(10,14)(12,18)(13,19)(15,17)(16,23)(20,24)(21,22)(25,27)(26,30)(28,29)(31,37)(32,39)(33,38)(34,35)(36,40) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,10,13,17)(11,15,19,14)(12,16,22,20)(18,24,21,23)(25,28,31,40)(26,32,34,38)(27,29,37,36)(30,39,35,33)(3,8)(5,6)(9,10)(11,15)(12,20)(13,17)(14,19)(16,22)(18,23)(21,24)(25,28)(26,32)(27,36)(29,37)(30,33)(31,40)(34,38)(35,39) involution — undirected(1,2)(3,5)(4,7)(6,8)(9,11)(10,15)(12,21)(13,19)(14,17)(16,23)(18,22)(20,24)(25,29,31,36)(26,33,34,39)(27,28,37,40)(30,38,35,32)(1,3)(2,6)(4,8)(5,7)(9,12,13,22)(10,16,17,20)(11,18,19,21)(14,23,15,24)(25,30)(26,27)(28,39)(29,32)(31,35)(33,40)(34,37)(36,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.